A chronic inflammatory disorder of the sebaceous glands which leads to the over-production of sebum. It involves the face, back and chest and is characterised by the presence of greasy, oily skin with enlarged pores, inflammation in and around the sebaceous glands, papules, pustules and, in more severe cases, cysts and scars.
Acne vulgaris is primarily androgen induced and appears most frequently at puberty and usually persists for a considerable period of time. Although it is commonly associated with teenage and adolescent skin, it can actually affect many age groups at different stages of life.
The scientific name of the bacteria that cause acne vulgaris is Proprionbacterium acnes.These bacteria are anaerobic, which means that they do not need oxygen to survive and grow. Although these bacteria are constantly present in all follicles in small numbers, they are prevented from reproducing to large numbers by the oxygen that is provided by an open follicle. However, once the follicle becomes blocked from the circulation of oxygen, these bacteria multiply and feed off of the sebum produced by the over-active sebaceous glands.
The typical stages of acne development are as follows:
Acne starts to develop when an increase in hormone production (commonly puberty) stimulates the sebaceous glands
Excess sebum production causes additional cell build-up in the follicles, which become comedones (plugs of sebum and dead cells)
The blocked follicle opening results in inflammation and irritation and the formation of papules
The blockage of sebum and dead skin cells prevents oxygen reaching the bottom of the follicle and hence bacteria form. The infected papules become pustules
The bacteria excrete an inflammatory fatty acid by-product which eventually results in blocking the follicle completely
The skin forms hardened tissue to prevent the spread of bacteria, creating cysts
The damage to collagen and elastin in the dermis can lead to depressed and raised scars (the scars resulting from cysts are called ice-pick scars)
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